A semiconductor device including a memory cell region where a memory cell such as a nonvolatile memory is formed on a semiconductor substrate has been widely used. As the nonvolatile memory, for example, the memory cell formed of a split-gate type cell using a MONOS (Metal-Oxide-Nitride-Oxide-Semiconductor) film is formed in some cases. At this time, the memory cell is formed by two MISFETs (Metal Insulator Semiconductor Field Effect Transistors) that region control transistor having a control gate electrode and a memory transistor having a memory gate electrode.
This memory gate electrode is formed by making a conductive film remain on a side surface of the control gate electrode via an insulating film in a sidewall spacer shape. An insulating film having a charge accumulating portion therein is formed between the memory gate electrode and the control gate electrode and between the memory gate electrode and a semiconductor substrate.
Japanese Patent Application Laid-Open Publication No. 2006-332143 (Patent Document 1) discloses a technique for a semiconductor device including a nonvolatile storage element formed in a semiconductor substrate, the nonvolatile storage element having a control gate electrode and a memory gate electrode provided adjacent to the control gate electrode.